The book "Air War over Spain" (Classic Serie Ian Allen) shows on page 50 an Ju 52 W from AS 88 (Code 527). From special interest is the fact of two MG-Positions, one over the third window and one at the normal position.

Both looks like field modifications! The first is very unique in desgin and the second use an 20mm Rheinmetall-Borsig MG C/30!! (same weapon as in Heinkel He 59)